Pipe suspension apparatus



Feb. 24, 1970 D. l.. GRULLER T AL A 3,497,243v

PIPE ssPENsIoN APPARATUS Filed Jan. 5, 196C l {Sheets-Sheet 2 .OV/Q/G/'U//ef .leona/Q f. W////a/27J INVENTORS BY l www f ATTO/PNEVJ Feb. 24,1970 Filed Jan. 5. 1966 D; l.. GRULLER ET AL PIPE SUSPENSION APPARATUS 4Sheets-Sheet 3 ATTO/WYE VJ United States Patent O 3,497,243 PIPESUSPENSION APPARATUS David L. Gruller and Leonard E. Williams, Houston,Tex., assignors to Cameron Iron Works, Inc., Houston,

Tex.

Filed Jan. 5, 1966, Ser. No. 518,580 Int. Cl. F161 37/00, 35/00 U.S. Cl.285-3 12 Claims ABSTRACT OF THE DISCLOSURE Apparatus for suspending oneor more concentric pipe strings at a level within a well intermediatethe wellhead and ,the lower ends of such strings, comprising an annularbody having means on its upper and lower ends for connecting it as apart of such pipe string and a seat on its outer side for landing itwithin a casing string of the well. At least one owway in the annularbody connects at its opposite ends above and below the seat for cementreturns when the annular body is landed in the casing string. There is arecess in the bore of the annular body having a downwardly and inwardlytapering surface and an annular seat means is movable vertically `withinthe recess. The seat means includes circumferentially separated segmentswhich slide downwardly and inwardly over the tapering surface of therecess upon movement of the seat means from an upper to a lowerposition. These segments define an opening in the upper position of theseat means to pass a drill string therethrough and an upwardly facingseating surface in the lower position of the seat means to provide asupport for a hanger body connected as a part of an inner pipe string asthe latter is lowered into the outer pipe string.V

This invention relates to apparatus for suspending concentric pipestrings Within a well. More particularly, it relates to improvedapparatus for suspending such strings at a level intermediate thewellhead and the lower ends of such string.

Apparatus of this latter type is useful in the drilling of offshorewells in which each casing string is suspended at a level near aformation capable of carrying its weight and then extended upwardly tothe wellhead located on a platform at water level. These upwardlyextending portions of the casing strings, which may be several hundredfeet long, are in turn suspended from the wellhead by conventional meanscomprising conically shaped hanger bodies seated upon correspondinglyshaped shoulders in the casing head. In the drilling `of an offshorewell with this type of apparatus, cement returns are circulated upwardlypast the intermediate suspension of the casing strings to the wellheadat water level.

After the well is tested and plugged, the platform including thewellhead equipment is removed for use at another location, the casingextension strings are backed off and retrieved from above theintermediate suspension level, and the well is capped. When it isdesired to complete the well, the cap is removed and the extensionstrings are lowered back into place and reconnected to the casingstrings suspended at the intermediate level.

In the drilling of a well, the operator runs as large a bit as possiblethrough at least the long strings of casing. For this reason, the lowersection of the casing string from the intermediate suspension level ondown must be free of obstructions. At the same time, it is mostdesirable that the casing extensions be of the same size as the lowersections of casings to which they are connected. For one thing, a largersize would require larger pressure control equipment at the wellhead, atleast during running of the casing extensions. Also, larger casing haslower pressure ratings than smaller casing. Thus, it

has not been the practice to suspend the casing strings from theseintermediate levels by conventional means, such as the previouslydescribed conically shaped hanger bodies which, of course, require acorresponding shaped obstruction upon which to seat.

Instead, it has been proposed to suspend the intermediate portions -ofthe casing strings by means of latches or dogs adapted to land withinrecesses formed in specially prepared annular bodies connected asintermediate parts of the next outer casing strings. Normally, theselatches are retracted as the inner casing string is run into the welland then expanded outwardly into the recesses by means of springs, camsor the like.

The main diflieulty with this sort of suspending apparatus is itsunreliability. Thus, after running the casing string on which thelatches are carried, the operator may find it impossible to expand thelatches into the recesses. This may be due to a purely mechanicalfailure, although drilling mud or other debris often ills the recess tosuch an extent as to prevent adequate expansion of the latches. Evenwhen fully expanded, these latches have low load capacity.

Also, of course, these latches are expensive to manufacture.

An yobject of this invention is to provide apparatus which, similarly tothat above-described, does not require an obstruction within the outercasing string during drilling therethrough, but which, on the otherhand, overcomes the shortcomings of such latch-type apparatus.

Another object is to provide such apparatus in which the inner string issuspended by means of a more or less conventional hanger body connectedas an intermediate part of the inner string and having a downwardlyfacing seating surface for landing upon a correspondingly shaped seat inthe outer casing string.

Still another object is to provide apparatus of the type described inthe foregoing objects which is reliable in operation, inexpensive tomanufacture, and has high load capacity.

These and other objects are accomplished, in accordance with theillustrated embodiment of the invention, by apparatus which includes,for use with such a hanger body for the inner string, an annular bodyconnectible as an intermediate part of the outer string and having aninwardly and downwardly tapering surface within a recessed portion ofits bore. An annular seat means is movable between vertically spacedapart positions within the recess and includes circumferentiallyseparated segments which are caused to slide downwardly and inwardlyover the tapering body surface upon movement of the seat means from itsupper to its lower position. In the upper position of the seat means,the segments dene an opening to pass the drill string therethrough,while, in their lower positions, they dene an upwardly facing seat toprovide a support for the hanger body on the inner string.

More particularly, in their upper positions, these segments define aminimum internal diameter through the seat means which is no less thanthe minimum internal diameter through the bore of the annular body.Thus, in such positions, they will pass the maximum size of drill stringwhich will pass the annular body. However, upon completion of drillingthrough the outer string and movement of such segments to their lowerpositions, they dene a seat having a minimum internal diameter less thanthe minimum internal bore diameter.

The seat means is releasably connected to the annular body for normallyholding such seat means in its upper position, so that it will not beaccidentally displaced to its lower position during the drillingoperation, as might occur due to engagement of the drill string or otherelements with the seat means. In the illustrated embodiment of theinvention, this connecting means comprises at least one shear pinbetween the annular body and th seat means.

In its preferred form, the seat means comprises a generally tubularmember having an upper cylindrical section to which the shear pin isconnected and being slotted about its lower end to dene thecircumferentially separated segments. The outer surfaces of suchsegments are so formed relative to the tapering surface within the boreas to facilitate swedging of the segments down along such surface. Whenthe segments are so swedged, their inner faces define a downwardly andinwardly tapering surface so as to provide a maximum of seating area fora correspondingly downwardly and inwardly tapering surface on the hangerbody for the inner string. The downward movement of the seat means islimited =by a shoulder'on the seat means abutable with a shoulder on theannular body prior to circumferential engagement of the segments withone another.

Upon completion of the drilling operation and prior to landing of thehanger -body for the inner string, the seat means is released from itsnormal connection to the annular body by means of a tool which islowerable into the outer pipe string for engaging the seat means,whereby it may be moved to its lower position. In the illustratedembodiment of the invention, the cylindrical portion of the seat meanshas threads about it for engaging with threads on the recessed bore ofthe annular body. More particularly, there is at least one Verticalgroove on the bore through the seat means with which an outwardly urgeddog on the operating tool is engageable so as to permit such tool toimpart torque to the seat means. This torque not only shears the pins soas to disconnect the seat means from the annular body, 'but also threadssuch seat means down in the body recess. There are suicient threads onthe body ybore to maintain this threaded engagement throughout theentire range of movement of the seat means so that such seat means is atall times engaged with the annular body. Thus, this threaded engagementnot only maintains the seat means in its upper position againstaccidental shearing of the pin, but also maintains it against accidentaldisplacement upwardly from its lower position and enables the seat meansto be move upwardly from its lower back to its upper position by reversemanipulation of the operating tool.

In the drawings wherein like reference characters are used throughout todesignate like parts:

FIG. 1 is a longitudinal sectional View of one-half of an inner casingstring suspended at an intermediate level within concentric outerstrings of a well of the character described and including an annularbody having seat means mounted therein which are constructed inaccordance with the above-described embodiment of the invention for usein suspending the next innermost casing to be run into the Well, suchseat means being disposed in its upper position to pass a full gaugedrill string therethrough;

FIG. lA is a cross sectional view of the casing strings shown in FIG. 1including the annular body and seat means connected as an intermediatepart of the inner string, and as seen along broken line 1A-1A of FIG. 1;

FIG. 2 is a view similar to FIG. 1 but showing a connector whichconnects the annular body with the upwardly extending portion of theinner string moved to a position in which cement or other debris may tbewashed from threads about the body to which the extension string may besubsequently connected upon completion of the well;

FIG. 2A is a cross sectional View of the casing strings including theconnector, annular body and seat means, as seen along broken line 2A-2Aof FIG. 2;

FIG. 3 is a perspective View of the seat means removed from within theannular body;

FIG. 4 is a longitudinal sectional View of the casing strings, as seenalong broken line 4 4 of FIG. 2A, and showing seat means lowered fromits upper position to its lower limited position by an operating toollowered through the inner casing extension into engagement with the seatmeans;

FIG. 4A is a cross-sectional View of the casing string with theoperating tool in place, as seen along broken line 4A-4A of FIG. 4;

FIG. 5 is another view similar to FIGS. 1 and 2, upon removal of theoperating tool from within the inner casing and lowering and suspensionof the next innermost casing string within the well by means of a hangerbody connected as an intermediate part thereof and supported upon thelowered seat means shown in FIG. 4; and

FIG. 6 is a view similar to FIG. 5, but in which a seat means mounted onthe hanger body of such next innermost casing string has been loweredfrom its upper to its lower position so as to provide a downwardly andinwardly tapering surface upon which a hanger body connected to a stillfurther innermost casing string may be supported.

With reference now to the details of the above-described drawings, anoutermost conductor casing 10 is connected at its upper end to a head 11which comprises an annular body landed near a competent formation at anunderwater level of an offshore well. More particularly, the conductorcasing and thus the head 11 are secured in place by a cement column (notshown) extending upwardly within the annular space between the casingand well bore. An extension 12 of the casing string 10 is threadedlyconnected at 13 to the upper end of the head 11 for extension upwardlyto suspension from the conventional wellhead (not shown) located on thedrilling platform at the water level As will lbe noted from thedrawings, the extension string 12 is of the same size as the downwardlyextending conductor casing string 10.

Upon drilling of the further hole through the conductor casing, anintermediate casing string 14 is lowered into the well bore and thensuspended at the level of casing head 11 by means of an annular hangerbody 15 having a downwardly and inwardly tapering surface thereabout forseating upon a correspondingly shaped surface 17 on the bore through thehead 11. As shown in FIG. 1, the lower end of hanger body 15 isthreadedly con nected to the upper end of intermediate casing string 14,and an extension 18 of casing string 14 is threadedly connected to theupper end of the body 15 for extension upwardly to suspension from thepreviously described wellhead at water level. This extension is of thesame size as the casing string 14.

Upon suspension of the intermediate casing, it is secured in place by afurther cement column within the annular space about it. Returns of thiscement are circulated upwardly to the wellhead at water level by meansof owways 19 formed about the outer surface of hanger body 15 to connectthe annular space about string 14 beneath such body with the annularspace between casing extensions 12 and 18. The lower end of theextension string 18 is connected to hanger body 15 by a tubularconnector 20 having its upper end threadedly connected to the lower endof the extension string and its lower end threadedly connected at 21 tothe upper end of hanger body 15. Threads 13 and 21, which may be lefthand, provide releasable connections between the casing stringextensions 12 and 18 and the bodies 11 and 15, respectively. Thisenables such extension strings to be backed off at the intermediatelevel when the well is to be capped.

Upon drilling of still further hole within the well bore, another casingstring 22 is run through the intermediate casing string 14 and extension18 and suspended therein by means of a hanger body 23 having an outerdownwardly and inwardly tapering surface 24 seatable upon acorrespondingly shaped surface 25 on the bore through hanger body 15 forthe intermediate string. An upwardly extending section 26 of the casingis connected to the hanger body 23 by means of a connector 27 forextension upwardly to the above-mentioned wellhead for suspensiontherefrom. As can be seen from FIG. 1, the casing string 22 and itsextension 26 are the same size.

The seats 17 and 25 in the hanger bodies restrict the full openingthrough the outermost and intermediate strings. However, it is notnecessary that these strings be full opening since the bit is not run tofull gauge in drilling through them.

Flowways 28 are formed about the outside of hanger body 23 and ilowways31 are formed about the connector body 27 so as to augment the annulusarea within casing 18. Thus, as in the case of the intermediate string14, the string 22 may be secured in place by a cement column extendingupwardly thereabout, and the returns from such cement column may becirculated upwardly through the owways 28 to the wellhead at waterlevel.

As shown in FIGS. l and 2, the connector 27 comprises an annular bodythreadedly connected at its upper end about the lower end of casingextension 26 and recessed about its lower end for disposal about anupwardly extending portion of the hanger body 23 above owways 28. Moreparticularly, there are threads 29 on the recessed lower end of theconnector body for engagement with threads 30 about the upwardlyextending portion of the body 23. These are preferably left hand threadsso that the connector permits the extension string 26 to be releasedfrom the body 23. In the position shown in FIG. l, the connector body isfully made up with the hanger body 23 so as to bring the upper end ofthe recess within the body into engagement with the upwardly extendingportion of the hanger body. At this time, seal rings 32 about the recessare in sealing engagement with the upwardly extending portion of thehanger body.

There are additional threads 33 formed about the upwardly extendingportion of the hanger body 23 beneath the threads 30 and upon a largerdiameter portion of such upwardly extending portion. These are righthand threads so as to provide a means for reconnecting a casingextension to the hanger body when it is desired to complete the well.Thus, as previously described, in the use of this apparatus, the casingextension 26 and its connector 27 will be removed from the hanger body23- so that a cap may be disposed thereover until such time as it isdesired to complete the well. Then, in completing the Well, a casingextension will be lowered back into position for reconnection to thecasing hanger body.

During the cementing operation, the returns will be circulated upwardlypast the threads 33, and this and other debris may clog the threads andmake it diflicult to later reconnect the casing extension to them. Slots34 are formed vertically through the threads 29 so that, upon raising ofthe connector 27 to the position shown in FIG. 2 by backing off thethreads 29, a suitable liquid may be circulated downwardly through suchslots and over the threads 33. Thus, in the upper position of the body27, the seal rings 32 are raised out of sealing engagement with theupwardly extending end of hanger body 23.

The bore through the annular body 23 has a recess intermediate its upperand lower ends 35 and 36, respectively, which, as can be seen from thedrawings, have minimum diameters equal to the diameter of each of thecasing string 22, its extension 26 and connector 27 therebetween so asto form a full opening therethrough. Thls recess includes an uppercylindrical portion having threads 37 formed thereabout and a lowerdownwardly and inwardly tapering surface 38 beneath such cylindricalportion. The lower end of the surface 38 terminates 1n an upwardlyfacing annular shoulder 39 which intersects the internal diameter of thelower end 36 of the body 23.

The seat means 40 disposed with the recess of the bore comprises agenerally tubular member having an upper cylindrical portion 41 providedwith threads 42 thereabout for engagement With the body bore threads 37and a plurality of circumferentially separated segments 43 dependingfrom the cylindrical portion. More particularly, the segments are formedbetween slots 44 extending upwardly from the lower end of the tubularmember. These slots are of equal width and equally spaced apart so thatthe adjacent segments are identical.

The upper outer surfaces 45 of the segments are recessed so as not tointerfere with the threads 37 on the body bore and the lower outersurfaces 46 thereof are tapered downwardly and inwardly on a steepertaper than the surface 38 on lower end of the body bore recess. vIn theupper position of the seat means shown in FIGS. l and 2, the innersurfaces of the segments define a cylindrical opening which is acontinuation of the inner diameter through the cylindrical portion 41 ofthe seat means. More particularly, the cylindrical opening thus definedthrough the seat means in its upper position has an internal diameter noless than the internal diameter formed through the upper and lower ends35 and 36, respectively, of the hanger body, as well as connector 27,and thus through the casing strings 22 and 26. In this manner, the seatmeans 40 will, in its upper position, pass any portion of the drillstring which passes through the casing strings 22 and 26.

However, as the seat means is moved from its upper to its lowerposition, as shown in FIG. 4, the outer surfaces 46 on the segments willslide downwardly and inwardly along surface 38 of the body bore recess.As can be seen from FIG. 4, this swedges the lower ends of the segmentinto a frusto-conical shape so that the inner surfaces thereof areflexed inwardly to form a downwardly and inwardly tapering seat withinthe hanger body having a minimum internal diameter less than the minimuminternal diameter through the casing strings. As previously noted,however, the seat means is not moved to this lower position until theoperator has finished drilling through the casing string 22, so thatthis inwardly projecting surface defined by the seat does not interferewith the drilling operations.

As can be seen from FIG. 4, in the lower position of the seat means, thelower ends of the segments 43 abut the upwardly facing shoulder 39 onthe lower end of the body bore recess. More particularly, this abutmentoccurs prior to engagement of the opposite sides of the slots 44 withone another. In this manner, the conical shape of the seat provided bythe inner faces of the segments is predetermined, regardless of thetolerances of the slots.

It will also be seen from FIG. 4 that the threads 37 on the body boreare of such length that the threads 42 on the cylindrical portion 41 ofthe seat means remain in engagement therewith during the movement of theseat means between its upper and lower positions. As previouslydescribed, this will maintain the seat means in its lowered positionagainst accidental displacement upwardly, as might otherwise be caused,for example, by engagement of casing collars with the lower ends of thesegments 43, especially during reciprocation of the casing for thepurpose of working scrapers about the casing against the well bore. Thecontinuous engagement of the threads 37 and 42 also permits the seatmeans to be returned from its lower to its upper position, in the eventthis becomes desirable, by a mere reversal of the operation to bedescribed to follow.

In the illustrated embodiment of this invention, the upper end of thehanger body includes an annular ring 35 threadedly engaged with anupward extension of the threads 37 on the recess of the hanger bodybore, in order to limit upward movement of the seat means and yet permitinsertion or removal of the seat means 40 with respect to the recessedportion of the hanger body bore. However, it is contemplated that suchring may be eliminated so as to leave the upper end of the recess open.In any event, the segments 43 are flexed inwardly a small amount topermit the maximum outer diameter of such segments to pass through thethreads 37 on the body bore.

As previously described, the seat means 40 is normally held in its upperposition by means of shear pins 46 connecting it to the hanger body 23.As shown in FIG. 3, there are several of these pins which extendradially from the outer side of the cylindrical portion 41 of the seatmeans. More particularly, these shear pins are inserted from the outerside of the upwardly extending portions of the hanger body 23. While thethreaded engagement between the seat means and the hanger body willnormally hold it against accidental displacement from its upper positiondue to downwardly directed impacts, the shear pins resist not onlydownward blows but also rotational forces to which the seat means mightbe subjected. This is especially true during rotation of the rotarydrill string which ordinarily may be expected to engage and rub againstthe inner surface of the seat means 40.

As also described previously, suflicient torque to shear the pins 46 isimposed upon the seat means by means of a tool lowerable through thecasing extension 26 for engagement with the seat means. Thus, as shownin FIG. 4, a tool having a body 47 suspended upon drill pipe 48 oranother running string 48 is lowered into a position in which dogs 49carried thereon are caused to engage within grooves 50 extendingdownwardly from the upper end of the seat means 40. As shown in FIG. 4A,these dogs 49 fit closely within the opposite sides of the grooves 50 sothat rotation of the tool body 47 through the string 48 will imparttorque to the seat means of suflicient magnitude to shear the pins 46and then lower the threads 42 along the threads of 37 so as to move theseat means from its upper to its lower positions.

As shown in FIGS. 4 and 4A, there are two locking dogs 49 each of whichis radially slidable within a recess 51 in the tool body 47. Moreparticularly, each such dog is urged outwardly by means of a coil springS2 disposed between the inner end of each recess and the opposite innerend of the dog 49. Such outward urging is limited by means of the pins53 which are removably disposed across each recess, as best shown inFIG. 4A.

The upper and lower ends 52 and 53 of the locking dogs are taperedinwardly from their maximum outer dimensions to corners which, in thelimited outward position of the dogs, are disposed to just inwardly oftool body recess 51. Thus, although the dogs are urged outwardly as thetool is lowered through the casing string extension 26, they do not havesquare shoulders which would tend to hang up in collars or otherrecesses within the casing string. Obviously, this is also true uponraising of the tool after its operation in moving the seat means fromupper to lower position. Thus, as can be seen from FIG. 4, for example,the Lipper tapered Iend 52 of the dogs will merely slide over the sharpcorner of the ring `45 of the hanger body as the tool is raised fromwithin the seat means.

In use, the tool is lowered to a position a short distance above thehanger body 23 and then slowly rotated as it continues to be lowered. Inthis manner, the operator knows when the tool has been engaged with theseat means, because he will encounter resistance to rotation as the dogs49 move into the grooves 50. He then continues to rotate the string 48so as to impart torque through the tool to the seat means 40 forshearing the pins 46 and then gradually threading the seat means downfrom its upper to its lower position. The operator knows that the seatmeans has been moved to its lower position inasmuch as the lower ends ofthe segments 43 will encounter the shoulder 39 and thus limit furtherrotation of the seat means. At this time, the operator may remove thetool 47 to enable running of the next inner casing string merely byraising the tool upon the string 48.

As best shown in FIG. 4A,'vertical grooves 54 are formed through thethreads 42 about the cylindrical portion 41 of the seat means. Thus,during lowering of the seat means from its upper to its lower position,drilling mud or other debris which may become caked in the threads 37 onthe body bore will be extruded upwardly through the grooves 54, and thusnot interfere with the downward movement of the seat means.

Along this same line, drilling mud and other debris has a tendency tobecome lodged within the slots 44 between segments 43. As best shown inFIG. 1A, these slots are tapered divergently inwardly in order toextrude at least part of this debris upon swedging of the segmentsinwardly during lowering the seat means.

Upon moving the seat means 40 to its lower position and removal of therunning tool 47 from within the casing string 26, the next inner casing55, shown in FIGS. 5 and 6, is run through the casing 22 and itsextension 26 so as to lower it into the hole drilled through casingstring 22. More particularly, when the casing string 55 has been solowered, it is suspended from the intermediate suspension for the casingstring 22 by means of hanger body 23a which is connected to the upperend of casing string 55. The lower end of casing string extension 56 isconnected to the upper end of hanger body 23a for extension upwardly tothe previously mentioned wellhead at water level. More particularly,extension 56 is connected to the hanger body 23a by means of a connector27a. When the string 55 has been so suspended, it is secured in place bymeans of a cement column thereabout, with the returns being circulatedupwardly through the annulus between the strings 22 and 55 and thencethrough flowways 28a formed in the outer surface of the hanger body 23ainto the annulus between casing string extensions 18 and 56.

As can be seen from FIGS. 5 and 6, the outer surface 24a of hanger body23a is tapered downwardly and inwardly correspondingly to the downwardlyand inwardly tapering surface defined by the inner faces of the segments43 of the seat means 40. Thus, as can be seen from FIG. 5, the maximumouter diameter of this hanger body is freely lowerable through thecasing extension 18, the upper end of the hanger body 23 and the uppercylindrical portion of the seat means 40, so that its downwardly andinwardly tapering surface 24a is free to move downwardly into seatinglengagement with the lowered seat means 40.

If desired, one or the other of the confronting tapered surfaces onhanger body 23 and hanger body 15 may be roughed, as by means of teeththereabout, in order to reduce the possibility of swedging the innerbody inwardly under load. One or the other of the confronting taperedsurfaces on hanger body 23a and segments 43 may, if desired, besimilarly treated to prevent bottlenecking of the inner body.

In the event the casing string 55 is the last one to be run, the hangerbody 23a may be of generally conventional conical construction. However,in the event a still further casing string is to be run through thestring 55, the hanger body 23a is constructed similarly to the hangerbody 23 in that it has a recess about the bore thereof to receive seatmeans 40a similar in construction and function to the seat means 40.Thus, as can be seen from a comparison of FIGS. 5 and 6, seat means 40amay, similarly to the seat means 40, be lowered from the upper fullopening position of FIG. 5 to the lower position of FIG. 6 to define adownwardly and inwardly tapering surface adapted to support acorrespondingly tapered surface on a hanger body connected as a part ofa still further inner casing string (not shown).

Since the parts of the hanger bodies and seat means thus correspond inconstruction and function, those of the apparatus connected as anintermediate part of the casing strings 55 and 56 carry numberscorresponding to those connected as an intermediate part of casingstrings 18 and 22 except for the addition of sub letter a. Obviously, adescription of neither the construction nor the operation of these partsneed be repeated herein. It is equally obvious that additional apparatusof this latter type may be provided upon additional inner casingstrings, as the need arises.

From the foregoing, it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forth,together with other advantages whtich are obvious and which are inherentto the apparatus.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations;

The invention having been described, what is claimed is:

1. Apparatus for use in suspending an inner pipe string having a hangerbody secured thereto within an outer pipe string of a well and providedwith a seating surface thereabout, comprising an annular body having awall means defining a bore therethrough and a downwardly and inwardlytapering surface within the bore wall, means on the annular body forconnecting it to the outer pipe string, and a generally tubular memberwithin said bore wall including.. an upper circumferentially continuouscylindrical section threadedly connected to threads on the bore wall formovement vertically between upper and lower positions therein and alower vertically slotted section delining circumferentially separatedsegments which depend from said cylindrical section and which slidedownwardly and inwardly along said tapering surface within the bore asthe tubular member moves from its upper to its lower position, the innerfaces of said segments defining a cylindrical continuation of theopening through said cylindrical section in the upper position of saidmember and a downwardly and inwardly tapering surface Corresponding tothe seating surface of the hanger body in the lower position of saidmember.

2. Apparatus of the character defined in claim 1, wherein said tubularmember has at least one groove extending vertically within its bore wallfor receiving part of a tool for transmitting torque to said tubularmember.

3. Well apparatus, comprising an annular hanger body having wall meansdefining a bore therethrough and a seat about its outer side and seatmeans on its bore wall for supporting an inner casing hanger, threadsabout the body above its outer seat, additional threads about a smallerdiameter portion of the body above the first-mentioned threads, and atool for running the hanger body including a body having internalthreads for engaging the additional threads of said hanger body, meansfor sealably engaging said tool with the hanger body above saidadditional threads when fully made up with said additional threads, andslots in the internal threads of the running tool body to permit thefirst-mentioned threads to be washed over when said running tool body israised to break said sealing engagement.

4. Apparatus for use in suspending an inner pipe string having a hangerbody secured thereto within an outer pipe string arranged within acasing string of a well having seating means therein, comprising anannular body having a wall means defining a bore therethrough and meanson its upper and lower ends for connecting it as apart of the outer pipestring, a seat on the outer side of the annular body for landing it onthe seating means 'within the casing string, a recess on its bore wallhaving a downwardly and inwardly tapering surface, and at least onelowway in the annular body connecting at its opposite ends above andbelow the seat, and annular seat means movable vertically within therecess and having circumferentially sepaarted segments which are causedto slide downwardly and inwardly over said tapering surface uponmovement of said seat means from an upper to a lower position, and meansto hold said annular seat in said upper position, said segments definingan opening in the upper position of the seat means to pass a drillstring therethrough and an upwardly facing tapered seating surface inthe lower position of the seat means to provide a support for the hangerbody as said inner pipe string is lowered into the outer pipe string.

5. Apparatus of the character defined in claim 4, wherein means to holdsaid annular seat means in said upper position comprises at least oneshear pin, between the annular body and the cylindrical section of theseat means.

6. Apparatus of the character defined in claim 4, wherein said annularseat means includes an upper cylindrical section from which thecircumferentially separated segments depend, and said means to hold saidannular seat means in said upper position comprises at least one shearpin between the annular body and the cylindrical section of the seatmeans.

7. Apparatus for use in suspending an inner pipe string having a hangerbody secured thereto within an outer pipe string arranged within acasing string of a well having seat Imeans therein, comprising anannular body having wall means defining a bore therethrough and meansthereon for connecting it to the outer pipe string, seat means withinthe casing string, a seat on the outer side of the annular body forlanding it on the seat means within the casing string, a recess in itsbore wall having a downwardly and inwardly tapering surface, at leastone fiowway in the annular body connecting at its opposite ends andabove and below the seat, annular seat means including an uppercylindrical section having threads thereabout engageable with threadsabout the recess of said annular body to permit said cylindrical sectionto be moved between an upper and lower position within said recessresponsive to rotation of said upper cylindrical section andcircumferentially separated segments depending from the cylindricalsection for sliding downwardly and inwardly over said tapering surfaceupon movement of said cylindrical section from its upper to its lowerposition, said segments defining an opening in the upper position of thecylindrical section to pass a drill string therethrough and an upwardlyfacing seat in the lower position of the cylindrical section to providea support for the hanger body as said inner pipe string is lowered intothe outer pipe string, means releasably connecting the upper cylindricalsection to the annular body in the upper position of said cylindricalsection to prevent its accidental displacement of said lower position,and a groove on the inside of the seat means for receiving a torquetransmitting tool lowered through said outer string in order to rotatesaid cylindrical section for releasing its connection to the annularbody and moving it from its upper to its lower position.

8. Apparatus for use in suspending an inner pipe string within an outerpipe string of a well, comprising an outer annular body connectible asan intermediate part of the outer pipe string and having wall meansdefining a bore therethrough with a downwardly and inwardly taperingsurface, a seat on the outer side of the outer body, seat means havingcircumferentially separated segments within said bore which are slidabledownwardly over said tapering surface between an upper position definingan opening through which a drill string may be passed and a lowerposition defining a downwardly and inwardly tapering seating surface,and means to hold said seat means in said upper position, an innerannular body connectible to the inner pipe string and having adownwardly and inwardly tapering surface thereon for landing upon saidseating surface as said inner body is lowered with said inner pipestring into said outer pipe string, and means for limiting downwardmovement of the seat means beyond said lower position, said outer bodyhaving at least one flowway connecting its outer side above and belowthe seat thereon.

9. Apparatus of the character defined in claim 8, wherein said innerbody has at least one flowway connecting its outer side above and belowthe-seating surface thereon.

10. Apparatus for use in suspending an inner pipe string having a hangerbody secured thereto within an outer pipe string and suspending theouter pipe string within a casing string of a well, comprising an outerannular body having wall means defining a bore therethrough and means onits upper and lower ends for connecting it as a part of a casing string,a seat 'within the bore wall of the outer body, an inner annular bodyhaving means on its upper and lower ends for connecting it as a part ofthe outer pipe string, a seating surface on its outer side for landingit on the seat on the outer body, at least one owway therein forconnecting the annular space between the casing string and outer pipestring, and a recess on its bore wall having a downwardly and inwardlytapering surface, and annular seat means movable vertically within therecess and having circumferentially separated segments which are causedto slide downwardly and inwardly over said tapering surface uponmovement of said seat means from an upper to a lower position, and meansto hold said annular seat means in said upper position, said segmentsdening an opening in the upper position of the seat means to pass adrill string therethrough and an upwardly facing seat in the lowerposition of the seat means to provide a support for the hanger body assaid inner pipe string is lowered into the outer pipe string.

11. Apparatus for use in suspending inner and outer pipe strings withina casing string of a well, comprising an outer annular body having wallmeans defining a bore therethrough and means on its upper and lower endsfor connecting it as part of a casing string, a seat within the boreWall of the outer body, an intermediate annular body having means on itsupper and lower ends for connecting it as a part of the outer pipestring, a seating surface on the outer side of the intermediate body forlanding it on the seat of the outer body, a recess in the bore Vwall ofthe intermediate body having a downwardly and inwardly tapering surface,annular seat means movable vertically within the recess and havingcircumferentially separated segments which are caused to slidedownwardly and inwardly over said tapering surface upon movement of Saidseat means from an upper to a lower position, and means to hold saidannular seat means in said upper position, said segments dening anopening in the upper position of the seat means to pass a drill stringtherethrough and an inwardly facing seat in the lower position of theseat means, an inner annular body having means on its upper and lowerends for connecting it as a part of the inner pipe string, and a seatingsurface on the outer side of the inner body for landing it on theupwardly facing seat of the seat means within the intermediate body, atleast one owway in the intermediate body connecting above and below theseat surface thereon, and at least one flowway in the inner body forconnecting above and below the seating surface thereon.

12. Apparatus of the character dened in claim 11, wherein there is arecess in the bore wall of the inner body having a downwardly andinwardly tapering surface, and an annular seat means is movablevertically within the recess, and has circumferentilly separatedsegments which are caused to slide downwardly and inwardly over saidtapering surface upon movement of said seat means lfrom an upper to alower position, and means to hold said last-mentioned annular seat meansin said upper position said segments deining an opening in the upperposition of the seat means to pass a drill string therethrough and anupwardly facing seat in the lower position of the seat means.

References Cited UNITED STATES PATENTS 2,607,422 8/1952 Parks et al.285-133 2,699,589 1/1955 i Redell 2li- 263.5 2,784,627 3/ 1957 Muelleret al. 285-39 3,090,640 5/1963 Otteman et al. 285-18 X 3,179,448 4/1965Jones 285-146 3,298,699 l/1967 Hall 285-18 X 3,334,923 8/1967 Putch285-3 X 3,335,799 8/1967 Miller 285-18 DAVID J. WILLIAMOWSKY, PrimaryExaminer DAVE W. AROLA, Assistant Examiner U.S. C1. XfR. 285-39, 141,322

